Police carried out a series of raids Tuesday in the area where the police officer was shot. A young man has been arrested in connection with the latest incident, but law officers have revealed few additional details.

Cengiz Azimkar and Mark Quinsey, the two soldiers killed in the attack at Massereene barracks, were due to be deployed to Afghanistan. The killings marked the first attack on British forces since 1997.

Mr. Orde's calls mirror those from politicians across Northern Ireland's political divide. Peter Robinson, leader of the hard-line pro-British Democratic Unionist Party, was adamant that the killings would not derail a process that has brought relative calm and prosperity after 30 years of conflict between pro-British Protestants and Irish Republican Roman Catholics. "Those responsible for this murderous act will not be allowed to drag our province back to the past," he said.

Local Sinn Féin legislator John O'Dowd extended his condolences to the victim's family and called the shooting "an attack on the peace process. It is wrong and it is counterproductive. … As with what happened in Antrim over the weekend we condemn it. Whoever carried out this shooting was not doing so to advance Irish republican or democratic goals. They have no strategy to deliver a United Ireland."

Some fear counterattacks by pro-British loyalist paramilitary groups. "We are staring into the abyss and I would appeal to people to pull back," Dolores Kelly, a moderate Irish nationalist SDLP lawmaker, told Sky Television.

A public employee in Belfast, who wished to remain anonymous, says of the violence: "It seems utterly senseless and arbitrary and has no backing from any section of any community. I'm a little scared of reprisals – it could create an opportunity for far-right loyalist groups, giving them an excuse to return to violence. The progress that has been made so far is better than what we had before."

Some dissident republicans are opposed to the Good Friday Accord that brought the power-sharing Northern Ireland Assembly and a shaky, but consistent peace to the streets after almost three decades of violence.

Some observers say that the dissident groups are trying to force the British Army back onto the streets in order to undermine Sinn Féin, the main republican party that is now in government in Northern Ireland.

Republican writer Liam O'Ruairc argues that the groups are not dissidents and are responding to Sinn Féin and the Provisional IRA's abandonment of armed struggle: "As a [Belfast] News Letter editorial noted: 'Sinn Fein also needs to sort itself out. The irony is that itis Adams, McGuinness et al who are the real dissident republicans, because they are the ones who have reached an accommodation with unionists and the British Government.'"

Mr. O'Ruairc says that the limited operational capacity of the small groups does not make them irrelevant. "The fact that CIRA and RIRA are tiny groups is of no consequence. What makes them relevant is that they are now an intrinsic part of the political equation. Their campaign might be limited in nature, especially compared to PIRA, but what matters is that it has determinate political effects.

"The fact that Gerry Adams called on nationalists to work with the forces of state that the IRA once tried to destroy proves how far they cannot claim the mantle of Republicanism."